"The project is going forward. It (the legal problem) is not impacting the Hoover Dam (bridge work) at all," said Ron Zeitz, a spokesman with the Federal Highway Administration, which is overseeing the $240 million project.

Obayashi's U.S. subsidiary, Obayashi USA LLC of Los Angeles, is partnering with PSM Construction USA Inc. of Burlingame, Calif. on $114 million in work to erect the bridge structure over the Colorado River, just south of the dam.

"Though it (Obayashi USA) is part of the company, it's an entity on its own point," Zeitz said.

The bridge project is already facing substantial delays following the collapse of a crane system critical to bridge work amid 55 mph winds last year. Originally set to open in 2008, the bridge is now expected to be complete no sooner than the end of 2010.

"They're back on track," albeit under a revised work schedule, Zeitz said.

When finished, the 1,905-foot span 890 feet above the river -- named the Mike O'Callaghan-Pat Tillman Memorial Bridge, in honor of the former Nevada governor and football star-turned-soldier killed in Afghanistan, respectively -- will carry U.S. Highway 93 traffic that crosses the dam.

The bridge itself is being designed to withstand winds of up to 100 mph. From the project's outset, wind was expected to be a major challenge in erecting the span.

The questions over the status of the dam work follows the recent announcement that Obayashi Corp. President Noriu Wakimura was giving up his post and Chairman Takeo Obayashi was accepting a demotion after an adviser and two other employees were arrested on suspicion of rigging bids for the construction of a waste plant in Hirakata City in 2005.

Earlier this year, Obayashi and four other builders were indicted for another alleged case of bid-rigging, involving a subway extension in Nagoya City. As a result, Obayashi and the other firms were briefly barred from handling Japanese government contracts.

The Hoover Dam contract is not part of that investigation and is not suspected of any improprieties, according to Zeitz.